The recommended expansion setting for solder mask is typically 2 mil (0.0508mm). This value is well-suited for standard production tolerances.
Here's a breakdown:
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Recommended Value: 2 mil (0.0508mm)
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Why 2 mil? This setting generally provides a good balance between exposing enough of the pad for soldering while still providing adequate protection to the surrounding board.
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Decreasing the Value: The expansion can be decreased from 2 mil, if needed, for specific design requirements.
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Increasing the Value: Increasing the solder mask expansion beyond 2 mil is generally not recommended as it can lead to insufficient solder mask coverage between pads.
In summary, stick with a 2 mil expansion unless your design necessitates a smaller value. Be wary of increasing it. Understanding Stop Mask Expansion (example link, replace with a real link if available) can provide additional context.
